All music genres have certain things that make them tick. Rhythms, instrumentation or structural conventions can all be part of what makes up music’s stylistic DNA.

Video game music – dating back to the late ’70s and early ’80s – is a young field in musicological terms but a fast-changing one.

“Video game music at one point in time was much more unique as a genre,” said Michelle Alexander. “The old video game sounds were entirely electronic and very much its own thing that matched the technology of the game.”

Alexander is a music analyst with Pandora. The Internet radio company uses analysts with backgrounds in musicology, performance or composition as part of its Music Genome Project to categorize music based on 450 different attributes for stations, including a station dedicated to video game music.

While once a more narrowly defined genre, Alexander said game music is now most comparable to film scores both in that it can mimic numerous styles to fit the tone of the game, but also that it tends to blend conventions of multiple music genres.

“Often times in terms of instrumentation, you'll have an orchestra or a faux orchestra ... but then you'll have a rock drum kit pounding away,” she said. “If you’re listening to a video game soundtrack or a film score soundtrack, you kind of always know where you are rhythmically. Whereas if you don't listen to much classical music, you might get totally lost.”

Game music varies widely. New installments of the Mario franchise might draw on the game’s 8-bit musical roots, while games like Halo look to more cinematic orchestral arrangements to help create a filmic quality for players. Generally speaking, however, game music places melody as king with driving but approachable rhythms and a simple harmonic language.

Those qualities often are influenced by American popular music. Alexander said that usually the popularity of the music has to do with the popularity of the game the music is from. The soundtrack to the popular 2011 game Skyrim is Pandora’s current top-playing piece of game music.

The musical form video game music takes is driven by what happens on screen.

“In terms of form [composers often] have to construct the music where it is able to loop easily because the player might stay in an area longer than the piece goes,” said Diego Gonzalez who is a music curator for Pandora.

In some ways, game composers must think of their audience as active participants in the way their music is performed. For some games this means writing music that doesn’t have a distinctive beginning or end so even the slowest player doesn’t become distracted by a track restarting a dozen times. In other cases composers make use of dynamic scoring where the music needs to smoothly transition to a new theme whenever the player reaches a new area or enters combat.

Other games make use of a technique called vertical re-orchestration, where a single piece of music plays throughout but changes instrumentation or keys (what musicologists call character variations) based on whether a player is walking through a serene field or battling enemy orcs.

The style of game music is starting to take hold outside of video games. Gonzalez said he sees early 8-bit music being covered with rock band instrumentation, and a genre called chiptune offers new 8-bit songs to indie rock fans who grew up playing Atari or early Nintendo games. Gonzalez also said Pandora is seeing an emerging genre called “epic,” which draws on more symphonic and grandiose film and video game scores.

“It's basically music that is composed to imitate those types of musicological forms, but it’s not associated with any game,” he said.

In the gaming world where spin-offs are a sign of success, the emergence of genres imitating video game music shows game composers are making their mark.